1. Field of the Invention
This invention relates to elevated floors, and more particularly to an improved adjustable pedestal for use in supporting panel members forming the elevated floor.
2. Description of the Prior Art
Elevated floors, also known as pedestal floors, provide a large unobstructed chamber through which the electrical wiring of various electrical services is distributed, and within which feed conduits for conditioned air extend. The chamber may also serve as a return air plenum. Elevated flooring incorporates plural pedestals which are uniformly distributed over a subfloor, such as a concrete floor of multi-story buildings. The pedestals cooperate in supporting the floor panels such that they are individually removable to gain access to the chamber there beneath. The panel members, as a group, provide a relatively, flat, high-strength floor which sustains walking and standing of personnel, supports apparatus and furnishings of the room, and supports moving loads as the apparatus and furnishings are introduced into the room or are altered and replaced.
It is highly desirable that the pedestals be capable of supporting the panel members in a level condition. However, since it is virtually impossible to construct a subfloor having a dead flat and level upper surface, vertically adjustable pedestals have been provided which are capable of compensating for the high and low areas normally exhibited by the subfloor. Typical examples of such vertically adjustable pedestals will be found in U.S. Pat. Nos. 3,025,934 (Spiselman et al), 3,084,911 (Spiselman), 3,279,134 (Donovan), 3,398,933 (Haroldson), and 3,681,882 (Bettinger). In addition to vertical adjustability, other pedestals have incorporated leveling means by which the head member or the support rod may be tilted to position the panel supporting surfaces of the pedestals in a common horizontal, that is level plane. The leveling means is intended to compensate for any surface irregularities of the subfloor. Typical examples of such pedestals will be found in U.S. Pat. Nos. 3,100,624 (Spiselman), 3,318,057 (Norsworthy), and 3,470,663 (Tate).
In all elevated floor structures, each panel member is intended to fit within an opening defined by the contiguous sides of adjacent panel members. To accomplish the required fit, it is necessary that each pedestal be secured to the subfloor precisely at a predetermined location. Out-of-position pedestals cannot be tolerated. Anticipating the possibility of out-of-position pedestals, the Norsworthy '057 pedestal utilizes a head member and a levelling pad presenting complementary spherical surfaces which cooperate to accommodate any divergence of the support rod from true vertical. An oversize cap member is provided presenting linear beads at its upper surface. The cap member is slideable laterally over the levelling pad to compensate for any deviations of the pedestal from its required location and to allow the linear beads thereof to be aligned with similar linear beads of adjacent pedestals. An adhesive is disclosed for securing the levelling pad to the head member and to the cap member. A slow-setting adhesive is preferred to allow sufficient time for levelling the levelling pad and for orienting the cap member prior to the development of a permanent bond. The Norsworthy '057 patent provides one arrangement capable of compensating for out-of-position pedestals. However, the arrangement has at least two distinct disadvantages both arising from the use of a slow-setting adhesive. First, the time required to complete the floor structure is extended. The panel members cannot be installed until after the adhesives have developed permanent bonds. Secondly, a misaligned and/or non-levelled support is produced if either the cap member and/or the levelling pad are inadvertently moved prior to the development of permanent adhesive bonds and such movement goes unnoticed. Since the adhesively secured head member, levelling pad and cap member constitutes an integral structure, the misaligned and/or non-levelled integral head assembly must be removed and the installation procedure repeated using newly provided head member, levelling pad and cap member.